System and Method for Topology Discovery and Fiber Continuity Verification in Network

ABSTRACT

An optical network includes an arrangement of optical nodes. An optical node of the arrangement, and corresponding method, perform optical connectivity discovery and negotiation-less optical fiber continuity verification in the optical network. An overall topology of optical connectivity provisioned for the arrangement is discovered by the optical node based on messages received from a management network communicatively coupling the optical nodes to each other. The optical node synchronizes, temporally and sequentially, with the other optical nodes based on the messages received, assigns fiber of the overall topology, based on a verification sequencing method, to verification slots of a verification sequence, and verifies continuity of fiber according to the verification slots of the verification sequence. The discovery, synchronization, and assignment operations enable the optical node and peer node to perform the optical fiber continuity verification in a symmetric, decentralized, and negotiation-less manner.

RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.16/730,396, filed Dec. 30, 2019. The entire teachings of the aboveapplication are incorporated herein by reference.

BACKGROUND

A network is a collection of network elements, such as computers,servers, mainframes, network devices, etc., that connected to oneanother to allow the sharing of data. There are many types of networks,such as electrical, optical, and radio frequency (RF) types of networks.

An optical network is a type of data communications network built withoptical fiber technology. The optical network utilizes optical fibercables as the primary communication medium for converting data andtransport data as light pulses between sender and receiver. An opticalnetwork is also known as an optical fiber network, fiber optic network,or photonic network.

The arrangement in which the network elements are connected together inthe network denotes the topology of the network. In an optical network,for example, the topology defines the arrangement of the multipleoptical fiber cables in the optical network. There are variousconfigurations for the topology of any type of network, such as a bus,ring, star, or mesh topology, etc.

SUMMARY

Embodiments of the present disclosure provide an optical network,optical node, method, and computer program product, that perform opticalconnectivity topology discovery and negotiation-less optical fibercontinuity verification. According to an example embodiment, a methodfor performing topology discovery and negotiation-less optical fibercontinuity verification in an optical network comprises announcing, viaa management network, a local topology (e.g., direct neighbors) ofoptical connectivity provisioned for a given optical node and statusinformation associated with a verification sequence to optical nodeswithin an arrangement of optical nodes of the optical network. Theoptical nodes within the arrangement are communicatively coupled via themanagement network.

The arrangement includes the given optical node and at least one otheroptical node. The local topology is local only to the given opticalnode. The method comprises discovering an overall topology, of opticalconnectivity provisioned for the arrangement, based on the localtopology and respective other local topology. The respective other localtopology is received from each optical node of the at least one otheroptical node via the management network.

The method comprises synchronizing with each optical node of the atleast one other optical node based on respective other statusinformation. The respective other status information is received fromeach optical node of the at least one other optical node via themanagement network and is associated with the verification sequence. Themethod comprises assigning fiber cables of the overall topologydiscovered to verification slots (e.g., steps) of the verificationsequence. The assigning is based on a verification sequencing method.The verification sequencing method is a same verification sequencingmethod employed at each optical node within the arrangement.

The method comprises verifying continuity of a given fiber cableaccording to a given verification slot (e.g., step) of the verificationsequence, autonomously and (a) absent negotiation between respectivecontrollers of the given optical node and a peer optical node of the atleast one other optical node and (b) absent negotiation between thegiven and peer optical nodes. The given fiber cable is (i) coupled, inthe overall topology, to a given optical port of the at least oneoptical port and to a peer optical port of the peer optical node and(ii) assigned to the given verification slot based on the verificationsequencing method. The respective controllers may be the same controlleror distinct controllers.

Another example embodiment disclosed herein includes an optical nodecorresponding to operations consistent with the method embodimentsdisclosed herein.

Another example embodiment disclosed herein includes an optical networkcorresponding to operations consistent with the method embodimentsdisclosed herein.

Further, yet another example embodiment includes a non-transitorycomputer-readable medium having stored thereon a sequence ofinstructions which, when loaded and executed by a processor, causes theprocessor to perform methods disclosed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing will be apparent from the following more particulardescription of example embodiments, as illustrated in the accompanyingdrawings in which like reference characters refer to the same partsthroughout the different views. The drawings are not necessarily toscale, emphasis instead being placed upon illustrating embodiments.

FIG. 1 is a schematic diagram of an example embodiment of an opticalnetwork that includes optical nodes performing topology discovery andnegotiation-less optical fiber continuity verification.

FIG. 2A is a block diagram of an example embodiment of two optical nodesin which an example embodiment of the present disclosure may beimplemented.

FIG. 2B is front view of an example embodiment of a set of optical nodesin a chassis in which an example embodiment of the present disclosuremay be implemented.

FIG. 2C is a block diagram of an example embodiment of four opticalnodes within which an example embodiment of the present disclosure maybe implemented.

FIG. 2D is an evolution of topology graph diagram of an exampleembodiment of different stages in the discovery of an overall topologyfor fiber continuity verification

FIG. 3 is a block diagram of an example embodiment of an optical nodeconfigured to perform topology discovery and negotiation-less opticalfiber continuity verification in an optical network.

FIG. 4 is a flow diagram of an example embodiment of a method forperforming topology discovery and negotiation-less optical fibercontinuity verification in an optical network.

FIG. 5 is a flow diagram of another example embodiment of a method forperforming topology discovery and negotiation-less optical fibercontinuity verification in an optical network.

FIG. 6A is a flow diagram of an example embodiment of the inner workingsof the method of FIG. 5.

FIG. 6B is a continuation of the flow diagram of FIG. 6A.

FIG. 7A is another flow diagram of an example embodiment of the innerworkings of the method of FIG. 5.

FIG. 7B is a continuation of the flow diagram of FIG. 7A.

FIG. 8 is a block diagram of an example internal structure of a computeroptionally within an embodiment disclosed herein.

DETAILED DESCRIPTION

A description of example embodiments follows.

It should be understood that the term “node” and its direct neighbor(i.e., peer node) as used herein may or may not be geographicallyco-located. A node may refer to a single communications module (e.g.,card, pluggable component, field replaceable unit (FRU), etc.), such asany of the individual communications modules installed in the chassis222 disclosed further below with reference to FIG. 2B. Alternatively, anode may refer to all of the communications modules installed within thechassis 222 of FIG. 2B. It should be understood, however, that nodesthemselves need not be geographically co-located. A node as disclosedherein corresponds to one single entity in a layer where a verificationsequencing method is applied. The layer can be the geographicalinterconnect, in which case the node corresponds to one geographicallocation. The layer can, however, be subcomponents all co-located at asame geographical location, in which case the node corresponds to asingle subcomponent. A node may be referred to herein as an apparatus,card, network element, component, line card, blade, data center, etc. Anode, as disclosed herein, is associated with a unique identifier (ID)and at least one port configured to transmit, receive, or transmit andreceive, payload data (e.g., payload traffic from user packets), asopposed to management data (e.g., management traffic) from a controller.While nodes may be referred to herein as being optical nodes coupled tofiber and employed in optical networks, it should be noted that thepresent disclosure is not limited to optical nodes, fiber connections,or optical networks. Any type of node, connection, or network may beemployed. For example, electrical connections or radio point to pointconnections fall within the scope of the present disclosure. As such, an“optical network” may be referred to herein as a “network,” an “opticalnode” may be referred to herein as a “node,” and a “fiber” or “fibercable” may be referred to herein as a “connection.” As such, an “opticalport” may be referred to herein as a “port,” etc.

In an optical network, such as the optical network 100 of FIG. 1,disclosed further below, it is useful to verify optical fibers couplingoptical nodes, automatically, without human intervention. Such opticalnodes may be any type of optical communications module, such as areconfigurable optical add-drop multiplexer (ROADM) type module,colorless/directionless (CD) add/drop type modules,colorless/directionless/contentionless (CDC) add/drop type modules,splitter/combiner type modules, or any other type of opticalcommunications module with optical port(s) for connecting opticalfiber(s) for optical communications.

FIG. 1 is a schematic diagram of an example embodiment of an opticalnetwork 100 that includes optical nodes performing topology discoveryand negotiation-less optical fiber continuity verification. The opticalnetwork 100 may include any number of optical nodes and is not limitedto the number of optical nodes of FIG. 1. Further, the optical network100 may have any suitable network topology, including but not limited toa point-to-point network topology, star network topology, mesh networktopology, tree network topology, or other type of network topology.

The optical network 100 may also be referred to interchangeably hereinas an optical communications network and may allow a large group ofwidely-distributed users to inter-communicate with each other, such asthe network users 102 a, 102 b, and 102 c. In the optical network 100,optical nodes may be connected directly to such network users, such asthe optical nodes 104 f-h.

In the optical network 100, the optical nodes 104 a-h employ opticalfiber, referred to simply as “fiber” herein, for transmitting payloaddata. Such payload data may originate from network users and betransported throughout the optical network 100 via the optical nodes 104a-h. According to an example embodiment, fiber in the optical networkcan be verified between nodes if management networks for the nodes areinterconnected for message delivery, such as disclosed below withreference to FIG. 2C. Referring back to FIG. 1, the optical nodes maysend and receive payload data via the fiber by selecting wavelengthsused for optically transporting the payload data. The optical nodes maysend and receive cable verification information via the fiber byselecting other wavelength(s) to transport such verificationinformation. The other wavelength(s) used for transporting the cableverification information are different from the wavelengths used fortransporting payload data. The cable verification information may begenerated using any method known in the art for verifying presence andintegrity of the fiber, which is a physical fiber and may also bereferred to interchangeably herein as a fiber “cable.” Informationexchanged to perform such verification may be any suitable information,such as power measurement information or other information that can beexchanged to determine physical continuity of fiber. According to anexample embodiment, optical nodes may share a chassis, such as thechassis 222 of FIG. 2B, disclosed further below.

An optical port of such an optical node may be coupled directly toanother optical port of the optical node or to a different optical nodevia a fiber cable. A pair of optical nodes coupled directly by a fibercable may be referred to herein as “direct” neighbors, that is, one nodeof the pair is a direct neighbor to the other node of the pair. Thefiber cable that couples the pair of optical nodes, directly, may bereferred to herein as a “direct” fiber cable. The direct fiber cable hasrespective endpoints that are connected to respective optical ports ofthe pair of optical nodes. While such respective optical ports may beprovisioned to be coupled in the overall topology of the optical network100, it is possible that the fiber cable therebetween is not physicallypresent or is faulty. Further, it may be that the respective opticalports are connected to fiber cables that are connected to other opticalports that are different from those or the overall topology. As such, itis useful to verify continuity of the fiber cable in an automated mannerin order to, for example, provide a fault notification or alarm when thefiber cable is not physically present or is faulty. The faultnotification or alarm may be provided, for example, via a user interfaceto a network operator(s) of the optical node.

An example embodiment includes a method for topology discovery innetwork. By announcing their own, and collecting distant, partialtopology information, optical nodes in the optical network 100 gainawareness of the total connectivity topology, which is subsequently usedfor intelligent, symmetric, decentralized, and negotiation-lesssynchronization of optical fiber continuity verification.

An example embodiment includes a method for negotiation-less fibercontinuity verification in the optical network 100. Negotiation-lesssynchronization of fiber continuity verification is achieved bydeploying an announcement and discovery messaging system, running over amanagement network (not shown), which may be an electrical managementnetwork. This messaging system forms a logical mesh between the opticalnodes in the optical network 100, while posing little requirements tothe physical structure and to the management hierarchy. According to anexample embodiment, messages (not shown) originating from optical nodesof the optical network 100 include partial topology information, localto each optical node, and sequence numbering, used for temporalsynchronization and data integrity verification.

By simply listening to incoming messages from any optical node in thesystem, each optical node can, autonomously, gain awareness of theoverall optical connectivity topology and can achieve temporalsynchronization with the other optical nodes in the optical network 100.The resulting overall topology now individually known to each opticalnode, and the resulting temporal synchronism then form the basis for thesynchronization of the entities participating in the fiber continuityverification. According to an example embodiment, virtually anyverification sequencing method can be deployed without the need forfurther communication or arbitration, as each optical node applies thesame verification sequencing method, disclosed further below, over theconsistent topology data, that is, the overall topology that isdiscovered.

In particular, an example embodiment addresses the optical fibercontinuity verification between multi-port optical nodes, that must besynchronized between both ends whenever the number of ports a opticalnode can verify simultaneously is restricted, such as disclosed furtherbelow with regard to FIG. 2A. This synchronization requires that theaggregate topology of the optical connections amongst optical nodes beconsidered. According to an example embodiment, fiber continuityverification is decentralized, symmetric, negotiation-less, and free ofany arbitration method and, therefore, addresses scalability,robustness, and performance issues.

FIG. 2A is a block diagram of an example embodiment of two opticalnodes, namely a first optical node 208 a and second optical node 208 b,that are coupled by a fiber cable 210 a. The first optical node 208 aand second optical node 208 b each include at least one optical port.For example, the first optical node 208 a includes a first plurality ofoptical ports 212 a and the second optical node 208 b includes a secondplurality of optical ports 212 b. It should be understood that the firstoptical node 208 a and second optical node 208 b may be optical nodes ofa same or different type. Further, it should be understood that arespective total number of optical ports shown to be included by thefirst optical node 208 a and second optical node 208 b may be the sameor different and is not limited to the respective total number shown. Inthe example embodiment, a third optical port 211 a of the first opticalnode 208 a is coupled to a second optical port 211 b of the secondoptical node 208 b via the fiber cable 210 a. The first optical node 208a and second optical node 208 b may be employed in a same or differentchassis, such as the chassis 222, disclosed below with reference to FIG.2B.

FIG. 2B is a front view of an example embodiment of a set of opticalnodes 220 in a chassis 222 in which an example embodiment of the presentdisclosure may be implemented. The set of optical nodes 220 includes aplurality of optical nodes that each include optical ports, some ofwhich are coupled to fiber cables as shown. The optical nodes of the setof optical nodes 220 are manufactured as printed circuit boards (PCBs)that are inserted into the chassis 222 and coupled to a backplane (notshown) of the chassis 222. For example, the PCBs may include respectiveconnector(s) that mate with connectors(s) located on the backplane.

The set of optical nodes 220 may include a controller 124 that may beconfigured to communicate over a management network (not shown) via thebackplane with other optical nodes in the set. The management networkmay be an electrical network that allows for inter-node communicationamong the optical nodes of the set and may be implemented via traces(not shown) of the backplane that may also be implemented as a PCB. Themanagement network may be communicatively coupled to other managementnetworks, thereby communicatively coupling the set of optical nodes 220to other optical nodes of other chassis.

Referring back to FIG. 2A, the first optical node 208 a includes atransmitter 214 and, optionally, a receiver (not shown). The secondoptical node 208 b includes a receiver 216 and, optionally, atransmitter (not shown). The transmitter 214 is a shared transmitterthat is shared among the first plurality of optical ports 212 a. Thetransmitter multiplexer 263 selects which optical port of the firstplurality of optical ports 212 a is coupled to the transmitter 214. Thereceiver 216 is a shared receiver that is shared among the secondplurality of optical ports 212 b. The receiver multiplexer 265 selectswhich optical port of the second plurality of optical ports 212 b iscoupled to the receiver 216. As such, the first optical node 208 a andsecond optical node 208 b can only send and receive verificationinformation, also referred to interchangeably herein as cable IDinformation, a single port at time.

For example, in order to verify continuity of the fiber cable 210 a, thefirst optical node 208 a is configured to couple the transmitter 214 tothe third optical port 211 a and, simultaneously, the second opticalnode is configured to couple the receiver 216 to the second optical port211 b. To verify all fiber cables coupled to respective optical ports ofthe first plurality of optical ports 212 a and respective optical portsof the second plurality of optical ports 212 b, the first optical node208 a and second optical node 208 b may verify such fibers by employinga scanning sequence. In the scanning sequence, optical ports of thefirst plurality of optical ports 212 a are coupled, sequentially to thetransmitter 214 and optical ports of the second plurality of opticalports 212 b are coupled, sequentially to the receiver 216. Therespective optical ports for coupling to the transmitter 214 andreceiver 216 are chosen such that eventually all possible port pairsfrom 212 a and 212 b are verified. Such sequential coupling on aport-by-port basis may be referred to herein as a “sweep.”

Fiber continuity verification between a pair of optical ports is atime-consuming process due to optical settling time. As such, it isuseful, for example, for fast alarming purposes, not to sweep and toonly perform fiber continuity verification for optical port combinationsthat are known to have a fiber cable provisioned therebetween. If,however, the first optical node 208 a and second optical node 208 b areto only perform fiber continuity verification for the optical portcombination with a provisioned fiber, synchronization is needed toensure that the participating optical nodes, namely the first opticalnode 208 a and second optical node 208 b, couple, simultaneously, thetransmitter 214 and receiver 216 to the third optical port 211 a andsecond optical port 211 b, respectively.

Such synchronization between the participating optical nodes may bebased on a known fibering structure provisioned for the optical network,that is, the topology for optical network. According to an exampleembodiment, disclosed further below with regard to FIG. 3, suchsynchronized fiber continuity verification can be performed by the firstoptical node 208 a and second optical node 208 b, autonomously, andabsent control over same by a controller(s), such as the controllers ofFIG. 2C, disclosed below.

FIG. 2C is a block diagram of an example embodiment of four opticalnodes within which an example embodiment of the present disclosure maybe implemented. The four optical nodes include the first optical node208 a and second optical node 208 b, disclosed above with regard to FIG.2A, and the third optical node 208 c and fourth optical node 208 d. Afiber cable 210 a is interposed between optical ports of the firstoptical node 208 a and second optical node 208 b. The first optical node208 a and second optical node 208 b are controlled by a first controller224 a. The first controller 224 a, first optical node 208 a, and secondoptical node 208 b are communicatively coupled via a first managementnetwork 226 a.

The third optical node 208 c and fourth optical node 208 d arecontrolled by a second controller 224 b. The second controller 224 b,third optical node 208 c, and fourth optical node 208 d arecommunicatively coupled via a second management network 226 b. A fibercable 210 b is interposed between optical ports of the third opticalnode 208 c and fourth optical node 208 d. The second controller 224 b,third optical node 208 c, and fourth optical node 208 d arecommunicatively coupled via a second management network 226 b. A fibercable 210 c is interposed between optical ports of the second opticalnode 208 b and third optical node 208 c.

In the example embodiment, a third management network 226 c couples thefirst management network 226 a and the second management network 226 benabling the first optical node 208 a and second optical node 208 b tobe communicatively coupled to the third optical node 208 c and thefourth optical node 208 d and vice versa. For example, the first opticalnode 208 a and second optical node 208 b may reside in a chassis, suchas the chassis 222 of FIG. 2B, disclosed above, and such chassis may bedifferent from a chassis that houses the third optical node 208 c andfourth optical node 208 d. As such, the third management network 226 cenables the first management network 226 a and second management network226 b to appear as a single communication domain.

For example, the first controller 224 a and second controller 224 b maybe coupled, for example, via the Internet and such communicate couplingof the third management network 226 c may be achieved via packetforwarding between the first controller 224 a and second controller 224b. The purpose of the third management network 226 c is not necessarilyto connect the controllers but is to allow messages from optical nodeson the first management network 226 a to be heard by nodes on secondmanagement network 226 b and vice versa (i.e., coupling of themanagement networks 226 a and 226 b). Such a coupling may however, beachieved by using the controller as a router, with an interconnectbetween the controllers. The messages sent out by optical nodes are notto be interpreted by the controller. Rather, the controller might simplyforward the messages, if the management network topology requires same.

In order to perform optical fiber continuity verification for the fibercables interposed the optical nodes, the first controller 224 a andsecond controller 224 b may negotiate in order to synchronize selectionfor optical ports to couple to a transmitter or receiver on the opticalnodes. As disclosed above with regard to FIG. 2A, the transmitter,receiver, or combination thereof employed by any optical node may be ashared resource.

As such, the first controller 224 a and second controller 224 b maynegotiate, that is, perform a handshake of communications with requestsand respective responses to the requests, in order to determine whichoptical port of the optical nodes is to be coupled to its respectivetransmitter or receiver at a given time. In response to completion ofsuch negotiation, the first controller 224 a and second controller 224 bmay communicate with the respective optical nodes they control such thatthe respective optical nodes can configure the negotiated selection andperform continuity verification in a synchronized manner. While suchnegotiation may mediate for selection that is limited to optical portsprovisioned to be coupled to a fiber cable, such negotiation is acentralized coordination method with limitations.

Centralized coordination of selected ports for fast fiber alarming haslimitation, such as scaling and single point of failure. Fiberinginformation might be distributed, and not readily available at onesingle point, and the management network may have a hierarchicalstructure. As such, coordination traverses several levels.

According to an example embodiment, each optical node has the knowledgeof the fibers that are directly connected to it, based on the localconfiguration data, received from the respective controller through themanagement network: local topology. Each optical node announces itslocal topology to the optical nodes on the management network. Suchannouncing may employ a broadcast message, multicast message, or anyother type of message that can be transmitted once and received by anyrecipient. Optical nodes listen to all announcements and collect thetopology information in order to discover an overall topology.

An example embodiment may include a unique identifier (ID) of thesending optical node as well as a unique ID of the message type intransmitted messages and may employ a resend request and responsemechanism to guarantee consistency between optical nodes. The unique IDof the message type may be referred to as a message type ID or, simply,as a message ID, that may identify, for example, whether the messageincludes an announcement message (status and/or topology information) orwhether it contains a resend request with a list of node ID(s) for whichstatus and/or topology information is missing. The announcement messagemay include a field that identifies which sequence number the sendingnode (i.e., node transmitting the message) is currently at, that is,synchronized to. This sequence number is used to synchronize the nodesin terms of temporal sequence slots of the verification sequence. Assuch, the message ID may be used as a heartbeat to guarantee temporalsynchronization between optical nodes. Sequential synchronization may beachieved based on all optical nodes having the same, consistent overall(i.e., total) topology, and each optical node applying the sameverification sequencing method to attribute every fiber of the overalltopology to a respective sequence number that is the same respectivesequence number at each optical node.

According to an example embodiment, each optical node applies a sameverification sequencing method to the overall topology they discover inorder to attribute every element (fiber) in the overall topology,deterministically, to a certain verification slot of the heartbeatsequence for verification. Because the verification sequencing method isdeterministic and the same across all optical nodes, each optical nodesassigns the same fibers to the same verification slots. Such an exampleembodiment has advantages. For example, the fiber continuityverification is decentralized, each optical node performs suchverification under its own control, that is, autonomously. The onlyinformation exchange needed is a heartbeat and topology. No point topoint communication is necessary between individual peers. The fibercontinuity verification is symmetric, that is, every optical node runsthe same method verification sequencing method. The fiber continuityverification is distributed. As such, any optical node can be removed atany time without affecting the operation of the other optical nodes.

It should be understood that the verification sequencing method can beany suitable sequencing method that assigns each fiber of the overalltopology, deterministically, to the verification slots of theverification sequence. The verification sequencing method ensures thatverification capabilities of each node are not exceeded. For example, ifan optical node has a shared transmitter, such as the shared transmitter214 of FIG. 2A, disclosed above, the verification sequencing methodensures that no verification slot that is verifying fiber to such a nodewould verify more than one fiber coupled to that node. According to anexample embodiment, the verification sequencing method may minimize atotal number of verification slots employed to verify all of the fiberin the overall topology while ensure that verification capabilities,such as transmit and receive capabilities, are not exceeded for anyoptical node in the arrangement. Regardless of what requirements areimposed on the verification sequencing method, the verificationsequencing method needs to be deterministic, that is, yield a sameoutput for a same input at any node. For example, the verificationsequencing method would yield the same fiber-to-verification-slotmapping at any optical node when applied to the same overall topology.

According to an example embodiment, the verification sequencing methodcould be described by a set of rules. For example, given a list of nodeID pairings {left node ID, right node ID} that identify node endpointsfor fibers (a fiber can be represented as a pair of ID's of the peers itconnects) in the overall topology:

-   -   Switch the left node ID and the right node ID of the fibers in        the list such that the node with the lower ID number is on the        left    -   Always sweeping the list of fibers from the top (first entry) of        the list to the bottom (last entry) of the list, attributing        (i.e., assigning) the first unassigned fiber to the lowest        sequence number for which the involved nodes are not yet busy.        The above set of rules will lead to the same sequence        (deterministic) on all the nodes and may be referred to as a        greedy method. It is said to be greedy because it sweeps the        list from top to bottom and, as soon as a fiber is found that        can be assigned, it is done so, greedily, not considering        whether this will lead to an optimal solution.

It should be understood that the verification sequencing method is notlimited to a greedy method and can be made to be more complex to find anoptimal solution with a least number of verification slots or moreelaborate to cater to specific needs. For example, the verificationsequencing method could assign more important fibers to multipleverification slots, such that those fibers are verified more frequentlyrelative to other fibers in the overall topology.

FIG. 2D is an evolution of topology graph diagram 250 of an exampleembodiment of different stages in the discovery of an overall topology242 for fiber continuity verification that may be employed in an opticalnetwork, such as the optical network 100 of FIG. 1. The stages include alocal configuration data stage 260 a, announcement stage 260 b, overalltopology stage 260 c, sequencing stage 260 d, and synchronizedverification stage 260 e. The local configuration data stage 260 a andannouncement stage 260 b enable discovery of the overall topology 242shown in the overall topology stage 260 c.

The evolution of topology graph diagram 250 is segregated into threecolumns that include a first column 252 a, second column 252 b, andthird column 252 c. The first column 252 a corresponds to a firstoptical node 258 a with an identifier (ID) of 4, that is “ID 4.” Thesecond column 252 b corresponds to a second optical node 258 b with ID7. The third column 252 c corresponds to a third optical node 258 c withID 9.

In the local configuration data stage 260 a, each optical node receivesits respective local topology. For example, first optical node 258 areceives the first local topology 234 a, the second optical node 258 breceives the second local topology 234 b, and the third optical node 258c receives the third local topology 234 c. In the local topologies, eachoptical node is represented as a circle with its corresponding IDincluded therein. In the evolution of topology graph diagram 250, linesbetween circles represent a fiber cable interposed between the opticalnodes represented by the circles.

In the announcement stage 260 b, each of the optical nodes announces itslocal topology to all other optical nodes that are communicativelycoupled to a management network. In the overall topology stage 260 ceach optical node has completed discovery of the overall topology 242 byjoining its own local topology with that of each respective localtopology announced by the other optical nodes in the announcement stage260 b.

In the sequencing stage 260 d, each optical node assigns each fiber ofthe overall topology 242 to a respective verification slot ofverification slots of a verification sequence based on a verificationsequencing method. The verification sequencing method is the sameverification sequencing method for each optical node. Each verificationslot may represent a time slot of the verification sequence. Eachverification slot may be associated with a sequence number thatrepresents, in time, a cycle of verification. All fiber assigned to thesame verification slot in the verification sequence would be verified ata same time. The verification sequencing method may be any method thatassigns all of the fiber in the overall topology, deterministically.

Following the sequencing stage 260 d, the optical nodes performsynchronized verification in the synchronized verification stage 260 e.In the synchronized verification stage 260 e, there are fourverification slots in the verification sequence assigned the ordinalnumbers 1, 2, 3, and 4. In the synchronized stage 260 e, fibers in theoverall topology 242 are shown as annotated with such ordinal numbers toindicate to which verification slot each fiber has been assigned by thesequencing stage 260 d.

In the synchronized verification stage 260 e, all optical nodes coupledto a fiber annotated with the ordinal number 1 would verify that fiberin the first verification slot of the verification sequence by turningtheir verification transmitter and receiver to the respective opticalport. All optical nodes coupled to a fiber annotated with the ordinalnumber 2 would verify that fiber in the second verification slot of theverification sequence. All optical nodes coupled to a fiber annotatedwith the ordinal number 3 would verify that fiber in the thirdverification slot of the verification sequence, and all optical nodescoupled to a fiber annotated with the ordinal number 4 would verify thatfiber in the fourth verification slot of the verification sequence. Itshould be understood that the total number of optical nodes, local andoverall topologies, fiber to verification slot assignments, etc., areshown for illustrative purpose and example embodiments disclosed hereinare not limited thereto.

Referring back to FIG. 1, the optical network 100 comprises anarrangement 130 of at least two optical nodes. The at least two opticalnodes includes a first optical node 104 a. The first optical node 104 ais associated with a first local topology (not shown) of opticalconnectivity provisioned for the first optical node 104 a. The at leasttwo optical nodes includes a second optical node 104 b. The secondoptical node 104 b is associated with a second local topology (notshown) of optical connectivity provisioned for the second optical node104 b.

The optical network 100 comprises a management network (not shown).Optical nodes within the arrangement 130 are communicatively coupled toeach other via the management network. The management network may behierarchical. In the optical network 100, the first optical node 104 aand second optical node 104 b are announcing, via the managementnetwork, the first and second local topologies, respectively, andrespective status information (not shown) that is associated with averification sequence (not shown). The first optical node 104 a andsecond optical node 104 b are discovering an overall topology of opticalconnectivity provisioned for the arrangement 130 based on the first andsecond local topologies. The overall topology may be referred tointerchangeably herein as a global topology. The first optical node 104a and second optical node 104 b are synchronizing to each other based onthe announcing.

The first optical node 104 a and second optical node 104 b are assigningfiber cables of the overall topology discovered to verification slots(not shown) of the verification sequence. The verification slots may bereferred to interchangeably herein as steps. The assigning is based on averification sequencing method. The verification sequencing method is asame verification sequencing method for both the first optical node 104a and second optical node 104 b. A given fiber cable (not shown) in theoverall topology is coupling optical ports (not shown) of the firstoptical node 104 a and second optical node 104 b. The given fiber cableis assigned to a given verification slot (not shown) of the verificationsequence based on the verification sequencing method. The first opticalnode 104 a and second optical node 104 b perform synchronized continuityverification of the given fiber cable, autonomously and (a) absentnegotiation between respective controllers (not shown) of the firstoptical node 104 a and second optical node 104 b and (b) absentnegotiation between the first optical node 104 a and second optical node104 b, by verifying the given fiber cable according to the givenverification slot of the verification sequence. The verificationsequence is based on the overall topology discovered, such as disclosedabove with regard to FIG. 2D.

FIG. 3 is a block diagram of an example embodiment of an optical node308 configured to perform topology discovery and negotiation-lessoptical fiber continuity verification in an optical network, such as theoptical network 100 of FIG. 1, disclosed above. The optical node 308comprises at least one optical port 312 configured to transmit, receive,or transmit and receive, payload data (not shown). The optical node 308comprises a management port 332 coupled to a management network 326.

Referring to FIG. 1 and FIG. 3, optical nodes within the arrangement 130are communicatively coupled to each other via the management network332. The arrangement 130 includes a given optical node, that is, thefirst optical node 104 a, and at least one other optical node, that is,the second optical node 104 b. The given optical node includes theoptical node 308. The optical node 308 comprises a processor 318.

The processor 318 announces a local topology 334 of optical connectivityprovisioned for the optical node 308 and status information 336associated with a verification sequence 340 to the optical nodes withinthe arrangement 130 via the management port 332. The processor 318discovers an overall topology 342, of optical connectivity provisionedfor the arrangement 130, based on the local topology 334 and respectiveother local topology 344 received from each other optical node of the atleast one other optical node via the management port 332. The localtopology 334 is local only to the optical node 308 and, as such, is theoptical node 308's “own” local topology 334. Each respective other localtopology 344 is local only to a respective other optical node of the atleast one other optical node.

The processor 318 synchronizes with each optical node (i.e., all) of theat least one other optical node based on respective other statusinformation 346 that is received from each optical node of the at leastone other optical node via the management port 332. The respective otherstatus information 346 is associated with the verification sequence 340.

The processor 318 assigns fiber cables of the overall topology 342discovered, based on a verification sequencing method, to verificationslots (not shown) of the verification sequence 340. The verificationsequencing method is a same verification sequencing method employed ateach optical node within the arrangement 130. The processor 318 verifiescontinuity of a given fiber cable 310 according to a given verificationslot 348 (e.g., present verification slot or current verification slot)of the verification sequence 340, autonomously and (a) absentnegotiation between respective controllers (not shown) of the givenoptical node and a peer optical node and (b) absent negotiation betweenthe given and peer optical nodes, such as the second optical node 104 b,of the at least one other optical node. The given fiber cable 310 is (i)coupled, in the overall topology 342, to a given optical port 311 of theat least one optical port 312 and to a peer optical port (not shown) ofthe peer optical node and (ii) assigned by the processor 318 to thegiven verification slot 348 based on the verification sequencing method.

The optical node 308 is associated with a given controller (not shown)of the respective controllers. The processor 318 is further configuredto discover the overall topology 342 by supplementing, for example, byjoining or aggregating, the local topology 334 with the respective otherlocal topology 344. For example, the overall topology may be discoveredby summing the local topology 334 with each respective other localtopology 344 received from each of optical node of the optical nodes inthe arrangement. The local topology 334 is received from the givencontroller via the management port 332. Each respective other localtopology 344 is received via a respective announcement message (notshown) that is communicated over the management network 326 by eachrespective other optical node.

The local topology 334 includes optical connectivity provisioninginformation for each optical port of the at least one optical port 312that is provisioned to be coupled to a respective peer optical port viaa respective fiber cable in the optical network 100.

According to an example embodiment, the processor 318 is furtherconfigured to announce the local topology 334, status information 336,or a combination thereof in a message (not shown) that is transmittedvia the management port 332 to the optical nodes in the arrangement 130.The message may be a one-to-many type of message that is transmittedonce and received by multiple recipients. According to an exampleembodiment, the message is a broadcast or multicast message. It shouldbe understood that the one-to-many type of message is not limited tobroadcast or multicast type of messages. The message may be referred tointerchangeably herein as a heartbeat message.

The status information 336 may include a sequence number. The sequencenumber may be referred to interchangeably herein as a heartbeat number.The processor 318 may be further configured to include a message typeidentifier (ID) (not shown) and unique ID (not shown) of the opticalnode in the message. The message type ID identifies a type of themessage. The sequence number identifies a present verification slot ofthe verification slots of the verification sequence 340 to which theprocessor 318 is synchronized. The processor 318 may be configured tocompute a checksum (not shown) for the message and append the checksumcomputed to the message. This useful to guarantee consistency of theoverall topology between all participating optical nodes.

The processor 318 may be further configured to compute a first checksum(not shown) for a message (not shown) received via the management port332. The message may include a message type ID and unique ID of thesending optical node of the message and may have a second checksum (notshown) appended thereto. In an event the first checksum computed doesnot match the second checksum, the processor 318 may discard themessage.

The processor 318 may be further configured to verify continuity of thegiven fiber cable 310 according to the given verification slot 348 ofthe verification sequence 340 and synchronized with the peer opticalnode, wherein the peer optical node includes the peer optical port.

The verification sequencing method assigns each fiber cable of theoverall topology 342, deterministically, to a respective verificationslot in the verification sequence 340. The verification sequencingmethod is deterministic and, as such, each optical node within thearrangement is caused to assign each fiber cable to a same respectiveverification slot relative to other optical nodes in the arrangementbecause all of the optical nodes in the arrangement apply the sameverification sequencing method to the overall topology 342 and theoverall topology 342 is consistent among all of the optical nodes in thearrangement. As such, all of the optical nodes derive the sameverification sequence defines an order for verifying all fiber cables inthe overall topology, and which fibers may be verified, in parallel,that is, within a same time slot.

The optical node 308 further comprises a transmitter (not shown),receiver (not shown), or a combination thereof, and a transmittermultiplexer (not shown), receiver multiplexer (not shown), orcombination thereof. The processor 318 may be further configured toprogress through the verification sequence 340 by transitioning betweenverification slots (i.e., steps) of the verification sequence 340 basedon received status information, that is, the respective other statusinformation 346 that is associated with the verification sequence 340.The received status information is transmitted by each optical node ofthe at least one other optical node via the management network 326 andreceived by the processor 318 via the management port 332. In an eventthe processor 318 transitions to the given verification slot 348, theprocessor 318 may couple the given optical port 311 to the transmitter,receiver, or combination thereof via the transmitter multiplexer,receiver multiplexer, or combination thereof, and verify continuity ofthe given fiber cable 310 assigned to the given verification slot 348.

FIG. 4 is a flow diagram 400 of an example embodiment of a method forperforming topology discovery and negotiation-less optical fibercontinuity verification in an optical network, such as the opticalnetwork 100 of FIG. 1, disclosed above. The method begins (402) andannounces, via a management network, a local topology of opticalconnectivity provisioned for a given optical node and status informationassociated with a verification sequence to optical nodes within anarrangement of optical nodes of the optical network, the optical nodeswithin the arrangement being communicatively coupled via the managementnetwork, the arrangement including the given optical node and at leastone other optical node, the local topology being local only to the givenoptical node (404). The method discovers an overall topology, of opticalconnectivity provisioned for the arrangement, based on the localtopology and respective other local topology received from each otheroptical node of the at least one other optical node via the managementnetwork, each respective other local topology being local only to arespective other optical node of the at least one other optical node(406). The method synchronizes with each optical node of the at leastone other optical node based on respective other status informationreceived from each optical node of the at least one other optical nodevia the management network and associated with the verification sequence(408). The method assigns fiber cables of the overall topologydiscovered to verification slots of the verification sequence, theassigning based on a verification sequencing method, the verificationsequencing method being a same verification sequencing method employedat each optical node within the arrangement (410). The method verifiescontinuity of a given fiber cable according to a given verification slotof the verification sequence, autonomously and (a) absent negotiationbetween respective controllers of the given optical node and a peeroptical node of the at least one other optical node and (b) absentnegotiation between the given and peer optical nodes, the given fibercable (i) coupled, in the overall topology, to a given optical port ofthe at least one optical port and to a peer optical port of the peeroptical node and (ii) assigned to the given verification slot based onthe verification sequencing method (412), and the method thereafter ends(414) in the example embodiment.

FIG. 5 is a flow diagram 500 of another example embodiment of a methodfor performing topology discovery and negotiation-less optical fibercontinuity verification in an optical network. The method begins (502)and synchronizes, temporally and sequentially, execution of fibercontinuity verification with other nodes in the optical network that areexecuting fiber continuity verification relative to a verificationsequence (504), assigns fiber in an overall topology of the opticalnetwork to the current (i.e., present) verification slot in a sequenceof verification slots of the verification sequence by assigning thefiber a respective ordinal number corresponding to a respectiveverification slot of the verification slots (506), verifies fiber at alocal node that is assigned a given ordinal number that corresponds to apresent verification slot of the verification, the present verificationslot transitioned to in the execution (508). The method checks forwhether fiber verification is still active (510) and, if so, returns to(504). If, however, fiber verification is no longer active, the methodthereafter ends (512) in the example embodiment.

FIG. 6A is a flow diagram 600 of an example embodiment of the innerworkings of (504) of the method of FIG. 5, disclosed above. The opticalnode implementing the example embodiment may be referred to as localnode within a context of FIGS. 6A and 6B.

FIG. 6B is a continuation of the flow diagram of FIG. 6A.

Referring to FIGS. 6A and 6B, the method begins (600) and increments theverification sequence number corresponding to a present verificationslot of a verification sequence (604) and creates and sends an outgoingtopology message that includes the local topology and the presentverification slot (606). The method waits for incoming messages (608).If an incoming message is received (610), the method checks for whetherthe message is a topology message (612). If yes, the method extractspeer status information from the message and updates the status of thesending peer (614). The method extracts topology data and updates theoverall topology (616). The method checks for whether all peers are upto date (618). If yes, the method thereafter proceeds to (506) of FIG.5, disclosed above, as (504) has completed. If, however, at (618) it isdetermined that there is at least one peer that is not up to date, themethod returns to wait for an incoming message (608).

If at (612), it is determined that the message is not a topologymessage, the method checks for the whether the message is a resendrequest (620). The resend request may be determined by extracting avalue for a message type ID from a message type ID field of the message.The value may be compared to the defined message type ID value for theresend type message. The defined message type ID value may differentfrom, for example, another value that is used to identify a message thatincludes local topology and status information. The resend message mayinclude a single or list of unique node IDs to which the resend messageis intended as well as a sequence number of a given verification slot ofthe verification sequence.

If it is determined that the message is not a resend request, the methoddiscards the message as having an unknown message type (626) and returnsto wait for an incoming message (608). If it is determined, however,that the message is a resend request, the method checks for whether theresend requests addresses the local node (622). If no, the methoddiscards the message (626) and returns to wait for an incoming message(608). If it is determined, however, that the resend request doesaddress the local node, the method retransmits a last topology messagesent (624) and returns to wait for further incoming messages (608).

Referring back to the creating and sending of the outgoing topologymessage at (606), the method further starts a deadline timer (628) inaddition to waiting for an incoming message (608). Following theexpiration of the deadline timer (628), the method checks if all peersare up to date (630). If not, the method creates and sends a resendrequest addressing all missing peers (632) and the method thereafterproceeds to (506) of FIG. 5, disclosed above, as (504) has completed.

FIG. 7A is a flow diagram 700 of an example embodiment of the innerworkings of (506) of the method of FIG. 5, disclosed above.

FIG. 7B is a continuation of the flow diagram of FIG. 7A.

Referring to FIGS. 7A and 7B, the method begins (702) and checks if allfibers in the overall topology have been assigned (704). If yes, themethod clears all assignments between fibers in the overall topology andverification slots in a verification sequence (706) and marks all peersas free (e.g., not busy) (708). This corresponds to the initializationof a new sequence, starting with verification slot 1 of the verificationsequence. If at (704) it is determined that not all fibers have beenassigned, the method marks all peers as free (e.g., not busy) (708).

Following the marking of all peers as free (e.g., not busy) (708), themethod finds a next fiber that has not yet been assigned (710) andchecks for whether an unassigned fiber has been found (712). If anunassigned fiber has not been found, the method thereafter proceeds to(508) as (506) has completed in the example embodiment. If, however, anunassigned fiber has been found, the method checks for whether bothpeers at endpoints of the selected fiber, that this, the unassignedfiber found, are free, that is, not presently verifying a fiber, (714)and the method marks the two peers as busy (716).

The method proceeds to assign the fiber for verification to a presentordinal number corresponding to the current (i.e., present) verificationslot in the verification sequence (718). The method then checks if allpeers are marked as busy (720). If yes, the method thereafter proceedsto (508) as (506) has completed in the example embodiment. If, however,all peers are not determined to be busy at (720), the method checks forwhether all fibers are assigned (722). If yes, the method thereafterproceeds to (508) as (506) has completed in the example embodiment. Ifno, the method proceeds to find a next fiber that is not yet assigned(710) and the method proceeds, as disclosed above.

An example embodiment of a method may include discovering and monitoringpresence of physical fiber connections between different optical nodesin a system. Such a method enables discovery and automatic provisioningof new fiber connections, monitoring and alarming of known (i.e.,provisioned) fiber connections, and measurement and reporting of theend-to-end transmission loss of monitored fibers. Such a method may bebased on heartbeat and topology discovery mechanism with associatedcommunication protocol. The method has the advantage of guaranteeingtemporal and sequential synchronization of optical cable verificationframe transmission and reception between different optical cards. Thisis achieved by providing the following main functionalities:

Announcement of the partial topology locally visible to each opticalnode (direct neighbors according to provisioning data).

Acquisition and maintenance of the global system wide topology byreceiving and interpreting the announcement from each optical nodecoupled to a management network.

Temporal synchronization of continuity verification transmission andreception by means of heart-beat (barriers) that cause the processor towait on messages.

Sequential synchronization of continuity verification transmission andreception by means of heart-beat (sequence numbers).

Based on discovering a consistent view of the overall topology and basedon the temporal and sequential synchronization, each node is able tocontrol cable verification transition and reception, with no need foradditional communication and handshaking. Based on a value of thesequence number (e.g., included in status information) each node canindependently determine what fiber a given cycle is used to verify andwhat port it needs to select in order to perform continuity verificationof the fiber determined. Based on the synchronization provided by theheartbeat mechanism and based on the overall topology discovered, thesequencing method determines what port-pairs (fiber connections) are tobe selected for signaling for every verification slot (e.g., time slot)of a verification sequence.

Heart-Beat and Sequencing

According to an example embodiment, temporal and sequentialsynchronization between peers is achieved using a global barrier methodas follows:

Each node keeps a track of all known partner nodes (peers), including:node ID, verification slot sequence number, and peer status. At the endof each verification slot (e.g., time slot) a peer sends messageannouncing readiness to pass to the next verification slot. The Nodewaits (barrier) until every peer has reported readiness. Once all peershave reported readiness the barrier can be crossed. There is no need toalert peers: they will know equally that all peers are ready. If somepeer falls behind due to lost messages, it eventual issues a resendrequest, and can follow. Other peers will be waiting at the nextbarrier. After passing the barrier, the node initiates a nextverification slot message. According to an example embodiment, anoptimization may not wait for all of the nodes to report readinessbefore transitioning to a next verification slot in the verificationsequence. For example, nodes that are not coupled by a fiber that isassigned to the present slot do not need to be waited on as they are notinvolved in the present verification slot that is being processed.Further, the only nodes that need to be waited on for a heartbeatmessage are those nodes that are involved in the current (i.e., present)verification slot verifying a fiber cable that is directly connected tothe local node that is verifying the fiber cable.

According to an example embodiment, a method for continuity verificationmay implement a dual cycle mechanism. On an odd cycle: the node mayprepare execution of step (port selection and Rx Tx configuration) andon an even cycle: execute step (transmission window).

According to example embodiments disclosed herein, peers will listen onthe network and will adjust their current sequence number to the highestobserved sequence number. If any node falls behind more than oneverification slot, it needs to skip forward to the present verificationslot. This guarantees that a node the that has fallen behind will notwait forever for messages that the other node can no longer send becauseit is already ahead. It also guarantees that a newly commissioned nodeis able to synchronize to the already existing heartbeat, that is, thepresent verification slot of the verification sequence.

Based on the provisioning data, peers are made aware of their localtopology (i.e., fiber connections to direct neighbor peers). Using thisinformation, and leveraging the heart-beat messages for communication,disclosed above, the peers work in synergy such that each can acquirethe overall topology. Each peer adds additional information to theheart-beat message, announcing their local topology. Peers extracttopology information from each other's heart-beat message, and join thisinformation into the overall topology. By using the heart-beat messages(delivery and integrity guaranteed) an example embodiment ensures thateach peer has the exact same view of the topology at the beginning ofeach verification slot. According to an example embodiment, localtopology is based on provisioning. The heart beat wait message indicatesthe sender's readiness to enter the next verification slot. In addition,it may be used to convey the sender's local topology information.

According to an example embodiment, a resend request message may be sentby a peer if it remains in a wait state for longer than a defined time.The peer or list of peers being waited for are identified in themessage. A peer receiving a resend request, responds with the last waitrequest it had sent out. If the receiver of this message already hascrossed the next barrier it may not answer the request. The waiting peerwill receive wait messages for the cycle after, and will know that itlost a cycle and needs to skip forward, that is, update its presentverification slot by setting it to a highest received sequence number.

FIG. 8 is a block diagram of an example of the internal structure of acomputer 800 in which various embodiments of the present disclosure maybe implemented. The computer 800 contains a system bus 802, where a busis a set of hardware lines used for data transfer among the opticalnodes of a computer or processing system. The system bus 802 isessentially a shared conduit that connects different elements of acomputer system (e.g., processor, disk storage, memory, input/outputports, network ports, etc.) that enables the transfer of informationbetween the elements. Coupled to the system bus 802 is an I/O interface804 for connecting various input and output optical nodes (e.g.,keyboard, mouse, displays, printers, speakers, etc.) to the computer800. A network interface 806 allows the computer 800 to connect tovarious other optical nodes attached to a network. The network interface806 may include a transmitter multiplexer (not shown) and receivermultiplexer (not shown) to switch coupling between a transmitter (notshown) an receiver (not shown) an respective optical ports (not shown),respectively. Memory 808 provides volatile or non-volatile storage forcomputer software instructions 810 and data 812 that may be used toimplement an example embodiment of the present disclosure, where thevolatile and non-volatile memories are examples of non-transitory media.Disk storage 814 provides non-volatile storage for computer softwareinstructions 810 and data 812 that may be used to implement embodimentsof the present disclosure. A central processor unit 818 is also coupledto the system bus 802 and provides for the execution of computerinstructions. The computer software instructions 810 may cause thecentral processor unit 818 to implement methods disclosed herein and thedata 812 may include, for example a local topology provisioned for aoptical node and an overall topology discovered for an optical network,such as the optical network 100 disclosed above.

Further example embodiments disclosed herein may be configured using acomputer program product; for example, controls may be programmed insoftware for implementing example embodiments. Further exampleembodiments may include a non-transitory computer-readable mediumcontaining instructions that may be executed by a processor, and, whenloaded and executed, cause the processor to complete methods describedherein. It should be understood that elements of the block and flowdiagrams may be implemented in software or hardware, such as via one ormore arrangements of circuitry of FIG. 8, disclosed above, orequivalents thereof, firmware, a combination thereof, or other similarimplementation determined in the future.

In addition, the elements of the block and flow diagrams describedherein may be combined or divided in any manner in software, hardware,or firmware. If implemented in software, the software may be written inany language that can support the example embodiments disclosed herein.The software may be stored in any form of computer readable medium, suchas random access memory (RAM), read only memory (ROM), compact diskread-only memory (CD-ROM), and so forth. In operation, a general purposeor application-specific processor or processing core loads and executessoftware in a manner well understood in the art. It should be understoodfurther that the block and flow diagrams may include more or fewerelements, be arranged or oriented differently, or be representeddifferently. It should be understood that implementation may dictate theblock, flow, and/or network diagrams and the number of block and flowdiagrams illustrating the execution of embodiments disclosed herein.

While example embodiments have been particularly shown and described, itwill be understood by those skilled in the art that various changes inform and details may be made therein without departing from the scope ofthe embodiments encompassed by the appended claims.

What is claimed is:
 1. An optical network comprising: a first opticalnode; and a second optical node, the first and second optical nodesperforming synchronized continuity verification of a fiber cableautonomously and absent negotiation, a) between respective controllersof the first and second optical nodes and b) between the first andsecond optical nodes, by verifying the fiber cable according to averification slot of a verification sequence, the fiber cable assignedto the verification slot of the verification sequence.
 2. The opticalnetwork of claim 1, wherein the fiber cable is a given fiber cable,wherein the verification slot is a given verification slot, and whereinthe optical network further comprises: an arrangement of at least twooptical nodes, the at least two optical nodes including the first andsecond optical nodes, the first optical node associated with a firstlocal topology of optical connectivity provisioned for the first opticalnode, the second optical node associated with a second local topology ofoptical connectivity provisioned for the second optical node; and amanagement network, optical nodes within the arrangement beingcommunicatively coupled to each other via the management network, thefirst and second optical nodes: announcing, via the management network,the first and second local topologies, respectively, and respectivestatus information associated with the verification sequence;discovering an overall topology of optical connectivity provisioned forthe arrangement based on the first and second local topologies;synchronizing to each other based on the announcing; assigning fibercables of the overall topology discovered to verification slots of theverification sequence, the assigning based on a verification sequencingmethod, the verification sequence method being a same verificationsequencing method employed at each optical node within the arrangement,the given fiber cable coupling optical ports of the first and secondoptical nodes in the overall topology, the given fiber cable assigned tothe given verification slot of the verification sequence based on theverification sequencing method.
 3. An optical node comprising: aprocessor, the processor configured to: perform synchronized continuityverification of a fiber cable with a peer optical node, autonomously andabsent negotiation, a) between respective controllers of the opticalnode and peer optical node and b) between the optical node and peeroptical nodes, by verifying the fiber cable according to a verificationslot of a verification sequence, the fiber cable assigned to theverification slot of the verification sequence.
 4. The optical node ofclaim 3, wherein the optical node is in an optical network, wherein thefiber cable is a given fiber cable, wherein the verification slot is agiven verification slot, and wherein the optical node further comprises:at least one optical port configured to transmit, receive, or transmitand receive, payload data; and a management port coupled to a managementnetwork, optical nodes within an arrangement of optical nodes of theoptical network being communicatively coupled to each other via themanagement network, the arrangement including the optical node and atleast one other optical node, the processor further configured to:announce a local topology of optical connectivity provisioned for theoptical node and status information associated with the verificationsequence to the optical nodes within the arrangement via the managementport, the local topology and status information being local only to theoptical node; discover an overall topology, of optical connectivityprovisioned for the arrangement, based on the local topology andrespective other local topology received from each other optical node ofthe at least one other optical node via the management port, eachrespective other local topology being local only to a respective otheroptical node of the at least one other optical node; synchronize witheach optical node of the at least one other optical node based onrespective other status information received from each optical node ofthe at least one other optical node via the management port, therespective other status information associated with the verificationsequence; assign fiber cables of the overall topology discovered toverification slots of the verification sequence based on a verificationsequencing method, the verification sequencing method being a sameverification sequencing method employed at each optical node within thearrangement, the given fiber cable (i) coupled, in the overall topology,to a given optical port of the at least one optical port and to a peeroptical port of the peer optical node and (ii) assigned by the processorto the given verification slot based on the verification sequencingmethod.
 5. The optical node of claim 4, wherein the optical node isassociated with a given controller of the respective controllers andwherein the processor is further configured to discover the overalltopology by supplementing the local topology with the other localtopology, the local topology received from the given controller via themanagement port, each respective other local topology received via arespective announcement message communicated over the management networkby each respective other optical node.
 6. The optical node of claim 4,wherein the local topology includes optical connectivity provisioninginformation for each optical port of the at least one optical port thatis provisioned to be coupled to a respective peer optical port via arespective fiber cable in the optical network.
 7. The optical node ofclaim 4, wherein the processor is further configured to announce thelocal topology, status information, or a combination thereof in amessage transmitted via the management port to the optical nodes in thearrangement, wherein the status information includes a sequence number,and wherein the processor is further configured to: include a messagetype identifier (ID) and unique ID of the optical node in the message,the message type ID identifying a type of the message, the sequencenumber identifying a present verification slot of the verification slotsof the verification sequence to which the processor is synchronized;compute a checksum for the message; and append the checksum computed tothe message.
 8. The optical node of claim 4, wherein the processor isfurther configured to: compute a first checksum for a message receivedvia the management port, the message including a message type ID andunique ID of a sending optical node of the message and having a secondchecksum appended thereto; and in an event the first checksum computeddoes not match the second checksum, discard the message received.
 9. Theoptical node of claim 4, wherein the processor is further configured toverify continuity of the given fiber cable according to the givenverification slot of the verification sequence and synchronized with thepeer optical node, wherein the peer optical node includes the peeroptical port.
 10. The optical node of claim 4, wherein the verificationsequencing method assigns each fiber cable of the overall topology,deterministically, to a respective verification slot in the verificationsequence and wherein the optical node and each other optical node arriveat a same fiber-to-verification slot mapping for each fiber cable byemploying the same verification sequencing method.
 11. The optical nodeof claim 4, wherein the optical node further comprises a transmitter,receiver, or a combination thereof, a transmitter multiplexer, receivermultiplexer, or a combination thereof, and wherein the processor isfurther configured to: progress through the verification sequence bytransitioning between verification slots of the verification sequencebased on received status information associated with the verificationsequence, the received status information transmitted by each opticalnode of the at least one other optical node via the management networkand received by the processor via the management port; and in an eventthe processor transitions to the given verification slot, couple thegiven optical port to the transmitter, receiver, or combination thereofvia the transmitter multiplexer, receiver multiplexer, or combinationthereof, and verify continuity of the given fiber cable assigned to thegiven verification slot.
 12. A method comprising: performing, by anoptical node, synchronized continuity verification of a fiber cable witha peer optical node, autonomously and absent negotiation, a) betweenrespective controllers of the optical node and peer optical node and b)between the optical node and peer optical node, by verifying the fibercable according to a verification slot of a verification sequence, thefiber cable assigned to the verification slot of the verificationsequence.
 13. The method of claim 12, wherein the optical node is agiven optical node, wherein the fiber cable is a given fiber cable,wherein the verification slot is given verification slot, and whereinthe method further comprises: announcing, via a management network, alocal topology of optical connectivity provisioned for the given opticalnode and status information associated with a verification sequence tooptical nodes within an arrangement of optical nodes of an opticalnetwork, the optical nodes within the arrangement being communicativelycoupled via the management network, the arrangement including the givenoptical node and at least one other optical node in the optical network,the at least one other optical node including the peer node, the localtopology being local only to the given optical node; discovering anoverall topology, of optical connectivity provisioned for thearrangement, based on the local topology and respective other localtopology received from each other optical node of the at least one otheroptical node via the management network, each respective other localtopology being local only to a respective other optical node of the atleast one other optical node; synchronizing with each optical node ofthe at least one other optical node based on respective other statusinformation received from each optical node of the at least one otheroptical node via the management network and associated with theverification sequence; assigning fiber cables of the overall topologydiscovered to verification slots of the verification sequence, theassigning based on a verification sequencing method, the verificationsequencing method being a same verification sequencing method employedat each optical node within the arrangement, the given fiber cable (i)coupled, in the overall topology, to a given optical port of the atleast one optical port and to a peer optical port of the peer opticalnode and (ii) assigned to the given verification slot based on theverification sequencing method.
 14. The method of claim 13, wherein thediscovering includes supplementing the local topology with the otherlocal topology, the local topology received from a given controller ofthe respective controllers, each respective other local topologyreceived via a respective announcement message communicated over themanagement network by each respective other optical node.
 15. The methodof claim 14, wherein the local topology includes optical connectivityprovisioning information for each optical port of the at least oneoptical port that is provisioned to be coupled to a respective peeroptical port via a respective fiber cable in the optical network. 16.The method of claim 14, wherein the announcing includes transmitting thelocal topology, status information, or a combination thereof in amessage transmitted via the management network to the optical nodes inthe arrangement, wherein the status information includes a sequencenumber, and wherein the method further comprises: including a messagetype identifier (ID) and unique ID of the optical node in the message,the message type ID identifying a type of the message, the sequencenumber identifying a present verification slot of the verification slotsof the verification sequence to which the given optical node issynchronized; computing a checksum for the message; and appending thechecksum computed to the message.
 17. The method of claim 14, furthercomprising: computing a first checksum for a message received via themanagement port, the message including a message type ID and unique IDof a sending optical node of the message and having a second checksumappended thereto; and in an event the first checksum computed does notmatch the second checksum, discarding the message received.
 18. Themethod of claim 14, wherein the verifying includes verifying continuityof the given fiber cable synchronized with the peer node according tothe given verification slot of the verification sequence, wherein theverification sequencing method assigns each fiber cable of the overalltopology, deterministically, to a respective verification slot in theverification sequence, and wherein the given optical node and each otheroptical node arrive at a same fiber-to-verification slot mapping foreach fiber cable by employing the same verification sequencing method.19. The method of claim 14, further comprising: progressing through theverification sequence by transitioning between verification slots of theverification sequence based on received status information associatedwith the verification sequence, the received status informationtransmitted by each optical node of the at least one other optical nodevia the management network; and in an event the progressing transitionsto the given verification slot, coupling the given optical port to atransmitter or receiver and verifying continuity of the given fibercable assigned to the given verification slot.
 20. A non-transitorycomputer-readable medium having encoded thereon a sequence ofinstructions which, when loaded and executed by a processor of a firstoptical node, causes the processor to: perform synchronized continuityverification of a fiber cable with a second optical node, autonomouslyand absent negotiation, a) between respective controllers of the firstand second optical nodes and b) between the first and second opticalnodes, by verifying the fiber cable according to a verification slot ofa verification sequence, the fiber cable assigned to the verificationslot of the verification sequence.